Why did l loose all my boosters when l swapped to my new phone?

Hi @carmencrawley welcome to the community and congrats on the new phone!

Mobile devices work a little differently to the game on Facebook. The boosters are saved in the old phones memory, not the game itself, so if you uninstall or change phones, they are lost. That's why King advise you don't save too many. Its so we can use them offline too which means they are not tracked. If you still have the old phone you could use them up there first though :)